Process tests shouldn't modify toy data

While working on TINKERPOP-1784 i noticed that process test suites modify the data in toy graphs. That works in the java suite because we can easily and quickly reload toy graph data between tests (though it can be expensive for some graphs). For GLVs it's slow and non-trivial to do this reload. To be consistent in the tests (especially while we have both test suites in place) we should make the java suite behave like the GLV and not mutate the static toy graphs so that they don't need to be cleared between runs. This might be helpful to java test suite users as well as it could given them a chance to speed up their builds.